1. Field of the Invention
This invention is in the field of RF (radio frequency) IC (integrated circuit) chip carriers for providing coupling between the terminal pads of a relatively small chip and the signal and power lines on a PC (printed circuit) board.
2. Description of the Prior Art
In low frequency IC chip carriers numerous problems exist due in part to the inherent difficulties of connecting the signal and power lines of a PC board to a relatively small IC chip having small closely spaced terminal pads. These problems include signal transmission lines having ill defined impedance and discontinuities causing multiple reflections that distort the waveform and degrade the noise margin, or signal to noise ratio. Cross talk between signal lines occurs degrading performance and causing false signals. The short rise time of digital signal waveforms results in noise spikes on adjacent signal lines. Also the characteristic impedance of the signal lines of the PC board is not properly matched to the impedance of the signal lines on the carrier, especially at the interface of the PC board and the carrier. Heat build up in the IC chip causes temperature related problems in chip performance. High impedance power lines are subject to spikes caused by large signal swings generated in the IC chip. Thus conventional carriers have disadvantages which have limited their operating properties and usefulness for high frequency (greater than 100 MHz) applications.